PHYSICAL CONDITIONS OF THE CLYDE SEA-AREA. 

 BY HUGH EGBERT MILL, D.Sc., LL.D. 



Position. The name Clyde Sea-area was introduced in order to group 

 together the estuary of the Clyde and all the sea-lochs along that part of the 

 coast of Scotland which is separated from the Atlantic by the protecting arm 

 of the peninsula of Kintyre. It lies within a line drawn from the Mull of 

 Kintyre to the Rinns of Galloway, and is included between the parallels of 

 55 5' and 56 17' N., and the meridians of 4 30' and 5 40' W., with a 

 connected water area of 1140 square miles. 



Configuration. The region consists of a lowland or seaward part, edged 

 mainly by gentle landslopes, from the sea to the Island of Bute, and of a 

 highland or landward part, in which the sea-water invades a series of long 

 valleys, branching on the whole northwards with a tendency either 

 towards the east or west. Two of these valleys, with an easterly and 

 a westerly trend respectively, are connected, forming the Kyles of Bute, 

 and others approach each other, such as Loch Goil and Loch Fyne or 

 the GareJoch and Loch Long. A depression of 30 feet would admit sea- 

 water to Loch Eck and Loch Lomond (both of which are filled with fresh 

 water) and would greatly lengthen all the sea-lochs by flooding the extensive 

 fiats at their heads. An upheaval of 30 feet, on the other hand, would 

 convert Loch Riddon, Loch Goil and the Gareloch into fresh water lakes, and 

 separate the Kyles of Bute into two lochs of typical form. 



In the infinite irregularity and variety of bare mountain slopes and deep 

 valley trenches, the uniform level of the smooth surface of the sea-lochs and 

 the broader reaches of the sea-area suggests a uniformity which does not really 

 exist. Could one remove the veil of water, the hollows it covers would 

 appear in their true character, scarcely less varied in outline than the land, 

 forming ridges, hollows, mountainous islands and shoals sometimes of 

 surprising steepness, and broad gently-sloping plains. The featureless 

 monotonv of the water is merelv a mask, but it has caused names to be 



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applied to different portions of the surface which do not correspond with the 

 natural regions outlined by the hidden features whose influence on the 

 regime of the water and its inhabitants is paramount. Hence for the pur- 

 pose of scientific description some liberties must be taken with the names 

 which appear upon ordinary maps, although we shall use these as far as 

 possible. The types of submarine configuration to be considered may be 

 restricted to the two simplest and most important plateaux or shallows 

 and basins or deeps ; and of these the Clyde Sea-area is made up as 

 follows : 



Natural Divisions. The Great Plateau forms a broad shelf or counter 

 across the mouth of the Area from the Mull of Kintyre to Ayrshire, a 

 distance of 30 miles, separating the wa.ter of the North Channel and Irish 

 Sea on the south (with depths over 80 fathoms) from the equally deep hollows 

 of the Arran Basin to the north. The contour-lines of 30 fathoms depth 

 inside and outside the Plateau are about 12 miles apart, and the Island of 



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